1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, a computer program, and a recording medium capable of combining an image and an illegal copy preventing pattern to output the combined image.
2. Description of the Related Art
As one of the illegal copy preventing patterns for preventing illegal or unauthorized copying, so-called embedded patterns have been used. FIG. 18 is a schematic block diagram of a conventional image processing apparatus capable of combining the embedded pattern as the illegal copy preventing pattern and an image and outputting the combined image. As shown in FIG. 18, the image processing apparatus generally includes an image input section 1, an image processing section 2 having an illegal copy preventing pattern generating section 2a, an illegal copy preventing pattern combining section 3, and an image output section 4. By this configuration, an input image input from the image input section 1 and an illegal copy preventing pattern generated in the illegal copy preventing pattern generating section 2a are combined in the illegal copy preventing pattern combining section 3 from which the combined image is output.
Also, as known techniques for printing an embedded pattern and generating an embedded pattern, there are inventions disclosed in Patent Documents 1 and 2 described below. Patent Document 1 discloses a print control method used in a printing system including a printer, an administrator host device, and a user host device, each connected to the others via a network. In this method, when a print instruction is transmitted from the user host device to the printer, a printer driver generating print data inquires about the administrative information stored in the administrator host device. Then, when the name of the user is found in the administrative information, the embedded pattern printing is performed.
On the other hand, Patent Document 2 discloses a method of generating an embedded pattern image used in an image processing apparatus generating the embedded pattern image including a latent image part and a background part. This method includes a determining step of determining the combination of the latent image pattern constituting the latent image part and the background pattern constituting the background part so that the printing density of the latent image part is substantially equal to that of the background part; an inputting step of inputting the determined latent pattern and background pattern, wherein color information determines the color of the embedded pattern image, input image information indicates an image to be processed, processing region information designates the region to be processed in the input image, region designating information designates the latent part and the background part, and camouflage region designation image information designates a white-background region; and a generating step of generating an embedded image based on each input information item.
Patent Document 1: Japanese Patent Application Publication No.: 2004-078752
Patent Document 2: Japanese Patent Application Publication No.: 2005-094326
However, unfortunately, the conventional techniques using an illegal copy preventing pattern as an embedded pattern may have a problem when there are no image data printed in the margin of a paper to be printed, since trimming of images is performed to generate a white-background region in the margin on the paper. In this case, since no illegal copy preventing pattern is printed in the peripheral region on the paper, an image reading device and an image processing device may perform a copy operation without recognizing the illegal copy preventing pattern. As a result, the function of the illegal copy preventing pattern may not be performed as desired since the image reading device and the image processing device cannot recognize an illegal copy.
Further, when there is a mismatch between the size of a unit pattern constituting a generated illegal copy preventing pattern and the size of the printing paper, and the mismatched illegal copy preventing pattern is printed on the paper, unfortunately, some unit patterns may be fragmented (truncated). As a result, similarly, the function of the illegal copy preventing pattern may not be performed as desired since the image reading device and the image processing device cannot recognize an illegal copy.